This invention relates to improved rotary actuators for turning a valve stem or other controlled element about an axis in response to earthquake forces or other shock forces.
Various types of actuators have been provided in the past for automatically closing a gas valve, or automatically actuating another controlled part, in the event of an earthquake. These devices typically include a weight which is displaceable by inertia effects relative to a carrier body or other part when the device is subjected to shock forces, and which acts to induce movement of an actuated element in response to displacement of the weight. Most of the devices of this type with which I am familiar have been designed to control a valve element having linear movement between open and closed conditions, though some have been capable of actuating a valve rotatively. In many instances, the devices have been of such construction as to function effectively with and require use of a specially constructed nonconventional valve, thus limiting greatly the possible field of application of the device.